Cylinder misfiring, Coil packs and ICM changed, not fixed

[McDub]

Hey all,

Long time not posting...

Thursday driving to work in my MKIV '03 gti i noticed a funny sound and a sublte reverberation at low rpms (~2000rpms).
After half an hour of driving it got worse, and it was clear that the engine was misfiring as it was lurching/jumping.

Took it to a local mechanic near work i've had a bit of work done at before. Probably more bmw guys but they still do plenty of vw work.
First diagnosis was a misfire in cylinder three and that coil pack 3 was gone, so was asked if i wanted to replace one or all four.
I went with all four. When it was time to pick up, was told it was better but not yet fixed and that the ignition control module needed to be replaced as well, and that it probably had been responsible for breaking the coil pack on cyl #3.

I needed to drive the car home that afternoon (planned on taking it back the next day) so asked them to put one of the old coil packs in cylinder three to stop damage to a new coil pack, and it was far worse than before, bunny hopping at low rpm when accelerating. I made it home on the freeway as it was ok at constant speed.

Then with the car off for a few hours, turned it back on and it drove perfectly for the final 20 minutes drive home.
Next day on the 1hr drive to work, first half was still perfect, then second half was jumping again similar to how it first started failing.

Took it back to mechanic who now had an I.C.M on it's way, and we'd decided that i'd just buy one of the new coil packs (to replace the one apparently damaged on cyl #3 and put the old ones on the other three cylinders), and the I.C.M. Picked it up after work apparently good to go, and it drove fine for the first half hour, but then started hopping slightly again at around 2800rpm.

So I'm really confused what is going on here. The fault is intermittent and changing a coil pack and I.C.M have not fixed the problem after $450.

What else might it be?

Oh, when they had four new coil packs in, they tried an I.C.M from a car next to it with it's own ecu (i.c.m delete perhaps), and it was apparently worse and they said that that icm must have been fried too...


Note: car has a custom code stage 1, other than that mostly stock (other than TIP, T.B with stock muffler, r1 diverter)

btw: can vcds lite detect engine misfires? I had a play around but couldn't detect any faults.

Cheers

[Lito]

Did you put new plugs in after the coil and icm were replaced? The misfiring could have fould the plug causing and intermittent mis?
Also have you checked for boost/vac leaks?

[Snail Style]

You would like to assume that they had swapped coils/plugs around first. I'd be taking it to a more competent mechanic who isn't just throwing parts at it and is actually diagnosing the problem.

[JustCruisn]

Coil pack usualy dont die it is the icm that goes. Make sure it has the heat sink on it and is attached to the air box properly.
Plugs would be a good thing to try next too, copper plugs are not too expensive.

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[h100vw]

Coilpacks on the mk4 are very robust. ICMs not so much. If a coilpack or the icm had failed. You'd be giving us " it sounds like a wrx" comments. Don't hesitate to ask me if you have dramas. It's a long time since it was tuned but I'll still give my time to resolve problems if you ask. �� I'd look at the plugs for sure. Bkr 7e $20 a set at a place near me. Very cheap to eliminate.

[Sirocco20348]

Sounds very familiar..... I encountered these symptoms on a few occasions. But the time that most closely matches what your saying was when my maf was dying. Unplug your maf and see if it idles and drives better. Obviously don't drive it hard. It was night and day for me as the car was undrivable with the maf connected. Once disconnected all good.

I bought genuine Bosch maf and Mayle icm and problem fixed. Icm probably didn't need to be changed but i did it anyway.